An integrated approach to stabilising HFN in wheat: screens genes & understanding

该项目的目的是提高哈格伯格下降数(HFN)的稳定性，这是小麦的一个主要品质性状。HFN目前对一些环境条件很敏感，这些环境条件降低了谷物的质量，使其不适合制作面包，给农民造成了严重的经济损失：去年(2004年)，英国种植面包的小麦作物中只有27%的质量是可接受的，农民每种植一英亩小麦估计损失100 GB。英国品种对低HFN的敏感性不同，部分原因是很难将传统的表型筛选应用于大群体的育种选择，但一些(例如。马六甲)显然具有足够的遗传抗性。高频氮的推荐评分依赖于适当的天气条件的发生，以触发潜在的敏感性，或顶灌以引发收获前发芽(McVittie J&Draper S(1982))或冬小麦立地灌溉，以评估品种对收获前发芽的易感性。J·纳顿。安装机器人。16：45-48)。该项目的一个关键目标是提供新的工具和生物学见解，使育种者能够从可用的英国精英种质池中鉴定出具有稳定HFN的新品系。现有的抗病品种在田间播种时没有表现出出苗问题，这一事实表明，这一目标与迅速建立林分是一致的。申请人之前的研究表明，英国谷物中α-淀粉酶水平高的两个最重要的原因是收获前发芽(PHS)和成熟前α-淀粉酶(PMA)。PHS是籽粒在穗中过早萌发的结果，在成熟期到收获期的潮湿天气促进了敏感品种的萌发。随后α-淀粉酶分泌到淀粉胚乳中，导致籽粒品质的恶化，这是通过HFN测试来衡量的。PMA的定义不是很清楚，但被认为是由于胚乳皱折区的糊粉层在籽粒发育后期不适当地产生了α-淀粉酶。在BBSRC资助的这个链接项目的目标范围内，我们打算研究小麦籽粒中导致PHS和PMA期间HFN减少的生化和分子事件。来自模式物种的分子遗传信息将被用来提供与萌发潜力/胚乳发育相关的“候选基因”。这些将用于测试种子发育过程中与PHS/PMA相关的功能。现有种质中候选基因的表达特征和遗传变异的特征，以及“智能筛选”和有效遗传标记的开发，将为英国小麦育种者提供资源，创造具有更稳定的HFN的改良品种。该项目将涉及BBSRC综合生物学和可持续农业战略计划目标的几个组成部分，包括“功能和比较基因组学”、“综合生物学-植物”、“转录学”、“整体生物生物学”和“可持续农业”。它的目标是提供一条“管道”，将从模式物种研究中获得的信息传递给用于增强育种种质的工具，这是最近BBSRC作物科学评论的关键建议。

The aim of this project is to improve stability of the Hagberg Falling Number (HFN), a major quality trait in wheat. HFN is currently sensitive to a number of environmental conditions that reduce the quality of grain and make it unsuitable for bread-making, resulting in severe financial losses to farmers: last year (2004) only 27% of the UK wheat crop grown for bread-making was of acceptable quality, with an estimated loss to farmers of £100 per acre of wheat grown. UK cultivars vary in their susceptibility to low HFN, partly due to the difficulty of applying conventional phenotypic screens to large populations of breeding selections, but some (eg. Option, Malacca) evidently carry adequate genetic resistance. Recommended List scores for HFN rely on the occurrence of appropriate weather conditions to trigger latent susceptibility or overhead irrigation to provoke pre-harvest sprouting (McVittie J & Draper S (1982) or irrigation of standing plots of winter wheat in order to assess varietal predisposition to pre-harvest sprouting. J. Natn. Inst. Bot. 16: 45-48). A key aim of this project is to furnish new tools and biological insights to enable breeders to identify new lines with stable HFN from the available pool of elite UK germplasm. The fact that existing resistant cultivars do not manifest problems with emergence in field sowings indicates that this aim is compatible with prompt stand establishment. Previous research by the applicants has shown that the two most important causes of high alpha-amylase levels in UK grain are pre-harvest sprouting (PHS) and pre-maturity alpha-amylase (PMA). PHS is the result of premature germination of grain in the ear, promoted in susceptible varieties by wet weather in the period between maturity and harvest. The consequent secretion of alpha-amylases into the starchy endosperm results in the deterioration in grain quality that is measured by the HFN test. PMA is less well defined, but is believed to result from inappropriate production of alpha-amylases by the aleurone layer in the crease region of the endosperm, late in grain development. Within the BBSRC financed objectives of this LINK project we intend to study the biochemical and molecular events in the wheat grain that are responsible for reduction of HFN during both PHS and PMA. Molecular genetic information from model species will be used to provide 'candidate genes' associated with germination potential/ endosperm development. These will be used for testing of function during seed development in relation to PHS/PMA. The characterisation of expression characteristics and genetic variation of candidate genes in existing germplasm, and the development of 'smart screens' and validated genetic markers will provide UK wheat breeders with resources to create improved varieties with more stable HFN. This project will address several components of the BBSRC strategic plan objectives for integrative biology and sustainable agriculture, including 'functional and comparative genomics', 'integrative biology-plant', 'transcriptomics', 'whole organism biology' and 'sustainable agriculture'. It will aim to provide a 'pipeline' for the delivery of information gained from studies in model species to tools for use to enhance breeding germplasm, a key recommendation of the recent BBSRC Crop Science Review.